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Palladium oxides in ultramafic complexes near Lavatrafo, Western Andriamena, Madagascar

Published online by Cambridge University Press:  05 July 2018

I. McDonald ,
D. Ohnenstetter ,
M. Ohnenstetter  and
D. J. Vaughan
I. McDonald
Affiliation:
Dept. of Earth Sciences, University of Manchester, Manchester M13 9PL, UK
D. Ohnenstetter
Affiliation:
CNRS-CRPG, 15 Rue Notre Dame des Pauvres, BP20 54501 Vandoeuvre les Nancy, France
M. Ohnenstetter
Affiliation:
CNRS-CRPG, 15 Rue Notre Dame des Pauvres, BP20 54501 Vandoeuvre les Nancy, France BRGM, Avenue Claude Guillemin, 45060 Orleans, Cedex 2, France
D. J. Vaughan
Affiliation:
Dept. of Earth Sciences, University of Manchester, Manchester M13 9PL, UK
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Abstract

Small (<2 km diameter), ultramafic intrusive complexes in the Andriamena region of Madagascar contain zones with disseminated chromite and sulphides which carry high concentrations of platinum-group elements (PGE). Assay of drill core from one complex, designated UM2, revealed three zones showing consistently high PGE grades. Mineralogical investigation of the UM2 core reveals that a small number of low reflecting, Pd-bearing platinum-group minerals (PGM) are present — always in association with a poorly characterized Pd stibio-arsenide [Pd3(Sb,As)] phase — in the shallowest of the three zones. Electron microprobe analysis of these PGM indicates the presence of oxygen and that at least two species exist. The resulting stoichiometries suggest that at least one species could be a hydrated form of palladinite [PdO.(H2O)n]. The other phase could be a hydroxide [Pd(OH)2] or a less strongly hydrated form of palladinite. Textural evidence suggests that the Pd-O species formed via the replacement of a precursor Pd-rich PGM, with only a limited removal of Pd, rather than via precipitation of a Pd-O PGM from a fluid that was Pd-bearing. The limited thermal stability of hydrated Pd oxides and the apparent restriction of the Pd-O phases to a shallow zone which is affected by the seasonal movement of groundwater, suggests that they may have formed at low temperatures via the leaching and replacement of other elements from a precursor Pd-rich PGM by oxygen and water during alternating water-saturated and dry conditions. If this is the case, the water table interface might be another environment, in addition to the surface, in which to look for the development of PGE oxides.

Keywords

platinum-group elementspalladiumoxygenhydrated oxidesAndriamenaMadagascar
Type
Research Article
Information
Mineralogical Magazine , Volume 63 , Issue 3 , June 1999 , pp. 345 - 352
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1999

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Footnotes

*

Present address: School of Earth & Environmental Sciences, University of Greenwich, Chatham Maritime, Kent ME4 4TB, UK.

References

Augé, T. and Legendre, O. (1994) Platinum-group element oxides from the Pirogues ophiolitic mineralization, New Caledonia: origin and significance. Econ. Geol., 89, 1454–68.CrossRefGoogle Scholar
Augé, T. and Maurizot, P. (1994) The Pirogues platinum mineralization of the Massif du Sud ophiolitic complex, New Caledonia. 7th International Platinum Symposium Moscow, p. 7-8 (abstract).Google Scholar
Augé, T., Maurizot, P., Breton, J., Eberle, J.M., Gilles, C., Jezequel, P., Meziere, J. and Robert, M. (1995) Magmatic and supergene platinum-group minerals in the New Caledonia ophiolite. Chron. Recherche Minière, 520, 3–26.Google Scholar
Cabri, L.J., Criddle, A.J., Laflamme, J.H.G., Bearne, G.S. and Harris, D.C. (1981) Mineralogy study of complex Pt-Fe nuggets from Ethiopia. Bull. Minéral., 104, 508–25.CrossRefGoogle Scholar
Clark, A.M., Criddle, A.J. and Fejer, E.E. (1974) Palladium arsenide-antimonides from Itabira, Minas Gerais, Brazil. Mineral. Mag., 39, 528–43.CrossRefGoogle Scholar
Cotton, F.A. and Wilkinson, G. (1988) Advanced Inorganic Chemistry. 5th edition, John Wiley.Google Scholar
Guerrot, C., Cocherie, A. and Ohnenstetter, M. (1993) Origin and evolution of the west Andriamena Pan African mafic-ultramafic complexes as shown by U-Pb, Nd isotopes and trace element constraints. (abstract) Terra Abstracts, 5, 387.Google Scholar
Jedwab, J. (1995) Oxygenated platinum-group-element and transition-metal (Ti, Cr, Mn, Fe, Co, Ni) compounds in the supergene domain. Chron. Recherche Minière, 520, 47–53.Google Scholar
Jedwab, J. (1997) Minéralogie des métaux du groupe du platine au Shaba, Zaire. In Colloque International Cornet: Gisements stratiformes de cuivre et mineralisations associees (Charlet, J.M., ed.). Acad. Royale des Sc. d'Outre-Mer., 325–55.Google Scholar
Jedwab, J., Cassedanne, J., Criddle, A.J., du Ry, P., Ghysens, G., Meisser, N., Piret, P. and Stanley, C.J. (1993) Rediscovery of palladinite PdO from Itabira (Minas Gerais) and from Ruwe (Shaba, Zaire). (abstract) Terra Abstracts, 5, 22.Google Scholar
Johnson, P.N. and Lampadius, W.A. (1837) Mittheilungen vermischten Inhsalts 1. Ueber brasilianisches Palladgold und dessen Ausbringen und Scheidung. J. Praktische Chemie, 11, 309–15.Google Scholar
Martel-Jantin, B., Eberle, M., Ohnenstetter, M. and Rakotomanana, D. (1991) Convention Platinoides Andriamena - Rapport technique de la mission 1988. BRGM Report, 32053, 126 pp. (unpublished).Google Scholar
McDonald, I., Vaughan, D.J. and Tredoux, M. (1995) Platinum mineralization in quartz veins near Naboomspruit, central Transvaal. S. Afr. J. Geol., 98, 168–75.Google Scholar
Milliotti, C.A. and Stumpfl, E.F. (1993) Platinum-group mineral inclusions, textures and distribution in the chromites of the Niquelândia complex, Brazil. 1st Brazilian PGE Meeting, 1993, 33–5.(abstract).Google Scholar
Nixon, G.T., Cabri, L.J. and Laflamme, J.H.G. (1990) Platinum-group element mineralization in lode and placer deposits associated with the Tulameen Alaskan-type complex, British Columbia. Canad. Mineral., 28, 503–35.Google Scholar
Ohnenstetter, M. (1996) Diversity of PGE in basic- ultrabasic intrusives — single model of formation. In Petrology and Geochemistry of magmatic suites of rocks in the continental and oceanic crusts. A volume dedicated to Professor Jean Michot (D. Demaiffe, ed.). Université Libre de Bruxelles, Royal Museum for Central Africa (Tervuren) publishers, 337–54.Google Scholar
Ohnenstetter, M. and Johan, Z. (1993) Classification of PGE deposits related to zoned mafic and ultramafic complexes. (abstract) Terra Abstracts, 5, 449.Google Scholar
Ohnenstetter, M., Johan, Z., Cocherie, A., Eberle, J-M., Martel-Jantin, B. and Rakotomanana, D. (1991) An infiltration metasomatism model for a new type of Pt-Pd mineralisation in Pan-African ultramafic complexes of Madagascar. (abstract) 6th Int. Platinum Symp., Perth 1990, 41.Google Scholar
Ohnenstetter, M. et al. (1994) New exploration methods for platinum and rhodium deposits poor in base metal sulphides. EU BRITE-EURAM project BE5793 Report 2, 45 pp. (unpublished).Google Scholar
Prichard, H.M., Ixer, R.A., Lord, R.A., Maynard, J. and Williams, N. (1994) Assemblages of platinum-group minerals and sulfides in silicate lithologies and chromite-rich rocks within the shetland ophiolite. Canad. Mineral., 32, 271–94.Google Scholar
Salpéteur, I. and Jezequel, J., (1992) Platinum and palladium stream-sediment geochemistry down-stream from PGE-bearing ultramafics, West Andriamena area, Madagascar. J. Geochem. Expl., 43, 43–65.CrossRefGoogle Scholar
Salpéteur, I., Martel-Jantin, B. and Rakotomanana, D. (1995) Pt and Pd mobility in ferralitic soils of the West Andriamena area (Madagascar). Evidence of a supergene origin of some Pt and Pd minerals. Chron. Recherche Minière, 520, 27–45.Google Scholar
Stumpfl, E.F. and Tarkian, M. (1974) Vincentite, a new palladium mineral from south-east Borneo. Mineral. Mag., 39, 525–52.CrossRefGoogle Scholar
Weiser, T. (1990) The quantitative proof of the existence of PGE-oxides. (abstact) 6th International Platinum Symposium, Perth, 52.Google Scholar
Wenner, D.B. and Taylor, H.P. (1974) D/H and 18/O16 studies of serpentinization of ultramafic rocks. Geochim. Cosmochim. Acta, 38, 1255–86.CrossRefGoogle Scholar
Westland, A.D. (1981) Inorganic chemistry of the platinum-group elements. In Platinum-Group Elements: Mineralogy, Geology, Recovery (Cabri, L.J., ed.). Canad. Inst. Min. Metall. Spec. Publ. 23, 5–18.Google Scholar
Wood, S.A. (1991) Experimental determination of the hydrolysis constants of Pt2+ and Pd2+ from the solubility of Pt and Pd in aqueous hydroxide solutions. Geochim. Cosmochim. Acta, 55, 1759–67.CrossRefGoogle Scholar